Japanese Laid-Open Patent Publication No. 60-162955 discloses an automatic analysis device for blood cells capable of automatically and simultaneously performing blood cell calculations and morphological cell classifications from the same sample.
This automatic cell analysis device is provided with an automatic cell classifying system for preparing a blood preparation by smearing a slide glass with blood from a blood sample and staining the smear then identifying and classifying blood cell images of a blood preparation, and an automatic cell calculating system for counting the number of blood cells in a fixed quantity of the blood cell sample, and the device simultaneously reports the blood cell calculation and blood cell classification results.
More specifically, in this blood cell analysis device, a preparation is enlarged by an optical microscope, a blood cell image is obtained with a camera, blood cell characteristics are calculated by a characteristic extraction circuit, and each type of blood cell is classified. Then, this blood cell analysis device counts the blood cells based on detection signals for hemoglobin concentration, white blood cells, red blood cells, and platelets.
In this blood cell analyzing device, when the blood cell count exceeds a normal range set beforehand in a microcomputer, a signal is sent from the microcomputer to an I/O controller as an abnormal value of the suspicious sample.
The I/O controller designates that the blood cell number of the blood cell classification is two or three times higher for a confirmed abnormal sample and for an ID preparation matching such a sample, or changes the blood cell examination method of the preparation to a method for detailed examination of a specific area having a high percentage of abnormal cells at an end part of the smear surface so as to increase abnormal cell detection sensitivity.
In this blood cell analyzing device, an abnormal cell is determined based on the “cell number” calculation information, the number of cells of the blood cell classification is designated two or three times higher, or changes the blood cell examination method for the preparation, however, a problem arises inasmuch as the abnormal sample determination via the number of blood cells may not have suitable condition settings for the designated blood cell numbers and the changed blood cell examination method.
Specifically, when a sample is determined to be abnormal based on the blood cell count, a sample which has abnormal blood cells but the blood cell count is normal can not be determined as an abnormal sample, such that the conditions can not be suitably changed.
Further, when a sample is determined to be abnormal based on a “blood cell count,” a sample that is normal is normal but has a blood cell count that somewhat exceeds the normal range with the appearance of abnormal cells may be determined to be an abnormal sample, such that the condition are unsuitably set.
That is, the blood cell count is one standard for determining an abnormal sample (for example, there may be suspicion of leukemia when the white blood cell count exceeds a normal number), but the blood cell count is not direct information indicating the possibility of the occurrence of abnormal cells in a sample, and is not a reliably standard for determining whether or not a sample is abnormal.
That is, even when the white blood cell count is increased for leukemia, the white blood cell count may be reduced to the normal range by chemotherapy or the like. In this case, conditions must be set for blood classification so that an abnormal sample has abnormal blood cells even when the number of white blood cells is in the normal range.
A white cell count that exceeds the normal range may occur even in healthy people without leukemia depending on their condition, and it is not desirable that the blood classification condition settings should unsuitably determine these as abnormal samples when the condition settings for blood classification might determine them as normal samples.
In the above automatic blood cell analyzer, when the number of blood cells exceeds the normal range, the blood cell count for blood cell classification is increased two or three fold, to make the blood cell count less than the normal range and other measures are not performed.
However, the following problems arise when the blood cell number is less than the normal range.
For example, in an automatic blood cell analyzer, a predetermined number (for example 100) of white blood cells must be imaged to classify white blood cells, and if there is a sufficient abundance of white blood cells in a sample, the white blood cells for imaging can be easily retrieved and imaged in a short time.
However, when a predetermined number of white blood cells must be imaged and there are few white blood cells in a sample, a long time is required to retrieve the required number of white blood cells in the sample, thereby lengthening the imaging time. Moreover, when the required number of white blood cells are not present in the sample, the imaging process is not completed.
Additionally, when imaging blood imaging is performed with auto focusing of the optical microscope using the red blood cell, which are the most prevalent component in the sample, as a standard; however, when there are very few red blood cells, such auto focusing can not be performed.